Magnetic resonance imaging (MRI) is widely used. An MRI image may be produced by exploiting a powerful magnetic field and radiofrequency (RF) techniques. During an MRI process, a plurality of acquired RF signals may be filled into k-space. The data in k-space may be transformed to reconstruct an MRI image. Echo planar imaging (EPI) is a fast imaging technique. A whole image may be produced within 30 milliseconds using EPI. The EPI technique may use a reverse direction frequency readout gradient to obtain one or more odd echoes and even echoes in turns. The odd echoes and even echoes in k-space may correspond to a plurality of MR signals acquired with opposite readout gradient polarities, respectively. Due to the eddy current induced by high-speed switching of the gradient magnetic field, phase inconsistencies (or phase errors) may be induced between the odd echoes and even echoes (or between the plurality of MR signals acquired with opposite readout gradient polarities). The existence of phase inconsistencies in k-space data may in turn generate Nyquist ghost artifact in a reconstructed image.
Nyquist ghost artifact may be common in images produced by EPI. One or more traditional techniques may only correct phase errors along a readout (i.e., frequency encoding) direction (also referred to as one-dimensional (1D) phase correction). However, residual artifacts may still exist after such a 1D phase correction. Thus, it is desirable to provide a two-dimensional (2D) phase correction technique to reduce or remove Nyquist ghost artifact.